Biochips such as a protein chip, peptide chip and DNA chip are widely used for diagnosis and research of various diseases. The biochips which have been widely used are usually obtained by immobilizing biologically relevant substances such as a protein, peptide and DNA on a glass substrate such as a slide glass.
However, the conventional biochips using the glass substrate were likely to cause non-specific adsorption and had a problem in accuracy of measurement. Also, since the glass substrate induces autofluorescence, measurements employing fluorescent labels which have been often used recently, had a problem in accuracy.
In order to solve these problems, a substrate for biochips, in which a carbon-containing layer having an active group(s) is formed on a metal substrate, and a biologically relevant substance(s) is/are bound to the active group(s), is provided (Patent Document 1). This substrate for biochips has excellent properties that autofluorescence is not induced, a biologically relevant substance(s) can be immobilized easily, processing of the substrate is easy, and high flatness and surface precision can be attained. Also, carboxyl group is exemplified as the active group. However, as a method employing carboxyl group as the active group, only the method in which amino groups are first bound to a carbon-containing layer, and then the amino groups are converted to diazonium ions, the diazonium ions are converted to nitriles, and the resulting nitriles are hydrolyzed, is disclosed, and the method is not concretely described.
Further, a substrate for biochips, in which an amino group-containing polymer is covalently bound on the substrate whose surface at least is composed of carbon, is also provided (Patent Document 2). The biologically relevant substance(s) is(are) covalently bound to the amino groups.